Ontogeny of the antibody response to cow milk proteins.

Twenty-nine infants were followed prospectively for the development of immunoglobulin G (IgG) and IgE antibodies to the cow milk proteins (CMPs) alpha-lactalbumin, alpha-casein, and beta-lactoglobulin. Thirteen infants were fed formula, eight were exclusively breast fed, and eight were breast fed with formula supplementation. By 4 months of life, infants fed formula or breast milk with formula supplementation had elevated IgE and IgG antibody levels to CMPs, when compared with values before 1 month of age. Further, breast-fed infants demonstrated significantly lower levels of IgE and IgG antibodies to CMPs than infants who received formula or breast milk with formula supplementation. Clinical symptoms of cow milk allergy were more common in infants fed formula or breast fed with supplementation, but were not significantly related to the presence of specific antibody. Our data suggest that the formation of CMP antibodies may reflect a normal humoral response following exposure to CMP antigens in this age group.